Generally, LED (Light-Emitting Diode), which is semiconductor light-emitting device, is manufactured by stacking semiconductor layers of mutually different conductive types on a growth substrate to sandwich an active layer therebetween and further by forming electrodes on the semiconductor layers of the individual conductive types. Manufactured semiconductor light-emitting devices are subjected to inspections for light emitting performance and the like so that acceptable devices are selected.
As inspections for light emitting performance of semiconductor light-emitting devices in their wafer state, there have conventionally been performed appearance inspections for inspecting the presence of flaws or the like under visible light, and light emitting inspections in which light emitting is performed by providing electric currents between positive and negative pad electrodes with use of a prober. In the light emitting inspection with a prober, since the needle (probe) of the prober needs to be put into contact with the electrodes of individual semiconductor light-emitting devices, there have been involved a quite long time for inspections and a fear of flaws on the semiconductor light-emitting devices due to the contact of the probe. Moreover, with small-sized semiconductor light-emitting devices, because their pad electrodes are also small in size, there has been difficulty in properly contacting of the probe with the devices.
Therefore, as a method of inspection for light emitting performance without providing electric currents through the semiconductor light-emitting devices, there has been proposed a method that the active layer of semiconductor light-emitting devices is excited with light irradiation and photoluminescence released from the excited active layer is observed.
For example, Japanese Unexamined Patent Application Publication No. 2009-128366 describes a light-emitting device inspection method including the steps of irradiating a semiconductor light-emitting device with ultraviolet light, capturing a light emitting image generated by photoluminescence effects in the active layer and the n-type semiconductor layer with use of a CCD (Charge Coupled Device) camera and, based on the hue or photoluminescence intensity information therefrom, determining quality of the semiconductor light-emitting device. In this inspection method, the quality is determined by taking advantage of the fact that when the emitting amount of blue light obtained by the photoluminescence effect from the active layer is small due to manufacturing defects or the like, the hue of emitted light observed as a color mixture with yellow light obtained by the photoluminescence effect from the n-type semiconductor layer differs from that of acceptable devices or the photoluminescence intensity as a whole is lower than that of acceptable devices.